Method of making a plurality of electronic assemblies

Abstract

A method of encapsulating a panel of electronic components such as power converters reduces wasted printed circuit board area. The panel, which may include a plurality of components, may be cut into one or more individual pieces after encapsulation with the mold forming part of the finished product, e.g. providing heat sink fins or a surface mount solderable surface. Interconnection features provided along boundaries of individual circuits are exposed during the singulation process providing electrical connections to the components without wasting valuable PCB surface area. The molds may include various internal features such as registration features accurately locating the circuit board within the mold cavity, interlocking contours for structural integrity of the singulated module, contours to match component shapes and sizes enhancing heat removal from internal components and reducing the required volume of encapsulant, clearance channels providing safety agency spacing and setbacks for the interconnects. Wide cuts may be made in the molds after encapsulation reducing thermal stresses and reducing the thickness of material to be cut during subsequent singulation. External mold features can include various fin configurations for heat sinks, flat surfaces for surface mounting or soldering, etc. Blank mold panels may be machined to provide some or all of the above features in an on-demand manufacturing system. Connection adapters may be provided to use the modules in vertical or horizontal mounting positions in connector, through-hole, surface-mount solder variations. The interconnects may be plated to provide a connectorized module that may be inserted into a mating connector.

What is claimed is: 
     
       1. A method of making a plurality of electronic devices, comprising:
 providing a plurality of mold panels, which when assembled, form an internal chamber; 
 providing a substrate having a plurality of conductive traces and a plurality of components electrically connected to form at least one circuit, the substrate having at least one contact for making an electrical connection to the circuit; 
 forming a panel assembly including the mold panels assembled with the substrate in the internal chamber and an encapsulant filling spaces between the substrate and interior surfaces of the chamber; 
 curing the encapsulant; and 
 cutting the panel assembly to expose at least a portion of the at least one contact and form a respective exposed contact. 
 
     
     
       2. The method of  claim 1  wherein the cutting comprises making a first cut in at least one of the mold panels, and in the first cut, making a second narrower cut through the panel assembly. 
     
     
       3. The method of  claim 2  wherein the curing comprises raising the temperature of the panel assembly and the first cut is made before the panel assembly cools after the curing. 
     
     
       4. The method of  claim 1  wherein the cutting divides the panel assembly producing at least one module having a plurality of layers including respective portions of each of the mold panels, the substrate, and the encapsulant, and the module contains the at least one circuit. 
     
     
       5. The method of  claim 4  wherein the cutting defines at least one side of the module. 
     
     
       6. The method of  claim 4  wherein the cutting defines two or more sides of the module. 
     
     
       7. The method of  claim 1  further comprising treating the exposed contact to protect against oxidation. 
     
     
       8. The method of  claim 7  wherein the treating comprises applying a removable conformal coating to the exposed contact. 
     
     
       9. The method of  claim 7  wherein the treating comprises applying a layer of metal to the exposed contact. 
     
     
       10. The method of  claim 9  wherein the applying a layer of metal comprises applying solder. 
     
     
       11. The method of  claim 9  wherein the applying a layer of metal comprises applying a precious metal. 
     
     
       12. The method of  claim 9  wherein the applying a layer of metal comprises plating. 
     
     
       13. The method of  claim 4  further comprising
 providing an adapter having at least one electrical terminal; and 
 attaching the at least one electrical terminal to the exposed contact. 
 
     
     
       14. The method of  claim 13  wherein
 the at least one contact comprises a plurality of contacts; 
 the module comprises a plurality of exposed contacts; 
 the adapter has a plurality of electrical terminals arranged to match respective ones of the plurality of exposed contacts; and 
 the adapter is mechanically secured to the module. 
 
     
     
       15. The method of  claim 4  wherein the mold panels are metal. 
     
     
       16. The method of  claim 15  wherein the respective portions of the mold panels provide heat sink surfaces for the module. 
     
     
       17. The method of  claim 1  wherein the providing mold panels further comprises providing contours in an internal surface of one or more of the mold panels. 
     
     
       18. The method of  claim 17  wherein the providing contours further comprises matching depths of portions of the internal surface to heights of one or more selected components. 
     
     
       19. The method of  claim 18  wherein the selected components include at least one magnetically permeable core and at least one semiconductor device. 
     
     
       20. The method of  claim 4 , wherein the traces and components are electrically connected to form a plurality of separable circuits arranged in a pattern on the substrate; and the cutting divides the panel assembly along spaces between the separable circuits into a plurality of modules each containing at least one respective circuit. 
     
     
       21. The method of  claim 20  wherein the spaces between the separable circuits have dimensions approximately matching a width of cuts produced by equipment used to cut the panel assembly. 
     
     
       22. The method of  claim 21  wherein the at least one contact comprises a plurality of contacts located in the spaces between the separable circuits. 
     
     
       23. The method of  claim 22  wherein the plurality of contacts are formed in the substrate. 
     
     
       24. The method of  claim 23  wherein the plurality of contacts are formed and buried below at least one surface of the substrate. 
     
     
       25. The method of  claim 15  further comprising treating at least one exterior surface of at least one of the mold panels for solderability. 
     
     
       26. The method of  claim 1  wherein forming the panel assembly comprises:
 dispensing encapsulant into a bottom panel mold; 
 assembling the substrate into the bottom panel mold; 
 dispensing encapsulant onto a top of the substrate; and 
 assembling a top panel mold onto the substrate. 
 
     
     
       27. The method of  claim 26  further comprising centrifuging the assembly before curing the encapsulant. 
     
     
       28. The method of  claim 1  wherein forming the panel assembly comprises:
 assembling the substrate with a first substrate surface facing into a first panel mold, 
 closing a second panel mold onto the substrate covering a second substrate surface, 
 providing one or more conduits to the internal chamber, and 
 forcing encapsulant through the one or more conduits into the chamber. 
 
     
     
       29. The method of  claim 28  further comprising centrifuging the assembly before curing the encapsulant. 
     
     
       30. The method of  claim 9  further comprising providing a connector for removably mating with and providing electrical connection to the metal. 
     
     
       31. The method of  claim 1  further comprising:
 providing a center plate having an opening to accommodate the substrate; and 
 wherein the forming a panel assembly includes positioning the substrate in the opening of the center plate and closing the mold panels against the center plate. 
 
     
     
       32. The method of  claim 31  further comprising providing at least one opening in the center plate connected to the internal chamber by at least one conduit; and
 forcing the encapsulant through the at least one opening and at least one conduit into the internal chamber. 
 
     
     
       33. The method of  claim 32  wherein the forming a panel assembly further comprises securing the mold panels together prior to curing the encapsulant.